The trove of Medicare data released Wednesday shows a wide cast of characters in the top ranks of the highest-reimbursed doctors, and reveals as much about the limits of the newly public billing records as it does about medical practice.

Among the highest-reimbursed doctors in their fields were a Michigan oncologist with $10 million in 2012 payments and a Rhode Island anesthesiologist at $3.5 million, both of whom have been indicted for fraud in federal courts. Also among the highest reimbursed was Jean Malouin, a...